Justifying and character positioning apparatus for electronic photo-typecomposing system



March 26, 1957 w. E. PEERY 2,786,400

JUSTIFYING AND CHARACTER POSITIONING APPARATUS FOR ELECTRONIC Fl-IOTO--TYPECOMPOSING SYSTEM Filed Oct. 5, 1949 14 Sheets-Sheet l INVENTOR. I n l'd/ WM5@ i ife/ March 26, 1957 w. PEERY 2,786,400

JUSTIFYING AND CHARACTER POSITIONING APPARATUS FOR ELECTRONIC PHOTO-TYFECOMPOSING SYSTEM IN VEN TOR. /f/rie i ffex March 26, 1957 W, E PEERY JUSTIFYING AND CHARACTER POSITIONING APPARATUS FOR ELECTRONIC PHQTO-TYPECOMPOSING SYSTEM Filed 0G13. 5, 1949 14 She'ets-Sheet 3 y BY 7M/MM d/m( March 26, 1957 E. PEERY 2,786,400 FYING AND CHARACTER POSITIONING APPARATUS FOR ELECTRONIC PHOTO-TYPECOMPOSING SYSTEM Filed oct. 5, 1949 JUSTI 14 Sheets-Sheet 4 March 26, 1957 w. E, PEERY 2,786,400

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IN VEN TOR. Waffe f ,0550/ MyW/ March 26, 1957 JUSTIFYING AND CHARACTER POSITIONING APPARATUS E. PEERY 2,786,400

FOR ELECTRONIC PHOTO-TYPECOMPOSING SYSTEM Filed Oct. 5, 1949 14 Sheets-Sheet 14 oaf/Par a; Ki?

I I I I I I I I I I I I l I I I I I I I I I I I I I I I I I f mM/f/y War# /Af rnv/ff @fn/vf l I l I I INVENTOR. Waffe ./f.' ff/ United States Patent O JUSTIFYING AND CHARACTER POSITIONING APPARATUS FOR ELECTRONIC PHOTO-TYPE- COMPOSING SYSTEM Walter E. Peery, Stamford, Conn., assigner to Time, In-

corporated, New York, N. Y., a corporation of New York Application October' 5, 1949, Serial No. 119,668

55 Claims. (Cl. 954.5)

The present invention relates to printing machinery and more particularly to photocomposing apparatus. More specifically, it has to do with a new and improved justifying and character positioning system for photocomposing apparatus, although it is not limited to such use.

The copending application Serial No. 41,318, tiled July 29, 1948, by the same inventor, for Electronic Photocomposing System, discloses apparatus for automatically printing selected text materials in columns of justified lines on a photosensitive emulsion. The present application is addressed to a high speed justifying and character positioning system which is of exceptional utility in photocompos-ing apparatus of the type described and illustrated in the said copending application.

The principal object of the invention is to provi-de a new and improved character positioning system for photocomposing apparatus or the like, which is characterized by high speed, accuracy, and facility in operation.

Another object .of the invention is to provide a new and improved character positioning system of the above character which includes means for automatically determining the correct spacing that must be inserted between words to insure that composition will be effected in properly justiied lines.

Yet another object of the invention is to provide a new and improved character positioning system of the above character which can accommodate characters of different widths.

A further object of the invention is to provide a new and improved character positioning system of the above character having means for automatically inserting the correct word spacing for line justification as a line `of type is being composed photographically.

Still another object of the invention is to provide a new and improved character positioning system of the .above character which insures uniform spacing of words throughout the composed line,

Additional objects and advantages of the invention will be apparent from the following detailed description of the typical form thereof taken in conjunction with the accompanying drawings in which:

Figs. la, 1b and lc, viewed side 'by side as one drawing comprise a flow diagram showing in block form the component circuits of a justifying and photocomposing system set up according to this invention;

Figs. 2a, 2b and 2c viewed side by side as one `drawing comprise a schematic diagram of the electronic circuits adapted to perform the respective functions of positioning or composing a plurality of characters in a line and establishing the word spacing necessary to justify the line. Shown also in this gure are electronic circuits which perform a resetting operation to prepare the system for the composition of each new line, and which control the inputs to the circuits of Figs. 3a and 3b to alternate the functions thereof in a manner to be described;

Figs. 3a and 3b, viewed side by side as one drawing comprise a schematic diagram f electronic circuits duplieating those of Figs. 2b and 2c and electrically connected r"ice thereto as shown by placing Figs. 3a and 3b beneathy Figs. 2a and 2b, respectively;

Fig. 4 is a drawing showing schematic circuits associated with the character positioning device and essential mechanical elements related thereto, the circuits of Fig. 4 being electrically connected to the circuits of Figs. 2a, 2b and 2c and 3a and 3b as shown by placing Fig. 4 beneath Figs. 3a and 3b;

Fig. 5 is a diagram showing the time relationships in the operation of that portion of the system performing the character positioning function;

Fig. 6 is a diagram showing the time relationships in the operation of the blanking circuits;

Fig. 7 is a diagram showing the time relationships in the operation of the system in performing its justifying the composing cycle of the system incorporating the circuit` `of Fig. 8.

For convenience, the invention will be described herein as adapted for use with an electronic Photocomposing system of the type disclosed in the aforementioned copending application. Portions of the photocomposing system not necessary for an understanding of the present- =invention will not be described in detail herein, general reference being made to the said copend-ing application for a disclosure of such matters.

In a photocomposing system of the type selected for purposes of illustration, a control or code tape 10 (Fig. la) carries, in code form, characters in sequences to be printed ultimately on a photosensitized strip or ilm 1.1 (Fig. 1c). The portion of the system which governs the selection and printing of the characters forms no part of the present invention and it will not be described in detail herein. Suiiice it to say that this part of the system acts in response to the coded characters on the tape to select for projection on the film 11 the successive characters to be printed; it is indicated in phantom in the iiow diagram .of Figs. la, 1b and lc,

More specifically, the character printing apparatus ncludes a rotating character disk 12 which carries individual characters inthe form of transparencies 12a spaced radially and circumferentially thereon. An optical system including a flashing lamp 13, a lens 14 and the reecting surface 15a of a rotatable mirror element 15, conveys images of characters (formed by the transparencies 12a) to the photographic iilm 11 to be printed thereon.

Thel mirror 15 is rotated as the composition of a line progresses, thereby to position successively projected character images in desired space relationship upon the film 11. In the system disclosed in the aforementioned copending application, rotation of the mirror 15 is effected by a pawl and ratchet mechanism operated by an electronic control system responsive to other code indicia on the tape 1t).

According to the present invention, the mirror 15 is rotated by an armature 16 disposed within pole pieces 17 of a galvanometer device 18 shown diagrammatically in Figs. 1 and 4. The armature 16 is adapted to be energized by electrical signals from a galvanometer control circuit 19 through the conductors 216, the direction of rotation of the armature 16, and consequently of the mirror 15 being dependent upon the direction of iloW of current. The mirror 15 is thus rotated in either direction and in K varying angular amounts depending upon the nature 0f arsenico the signal received from the galvanometer control circuit 19 in the form, for example, of negative and positive pulses, more fully described in the ensuing text under the subheading VL Galvanometer control circuits, to follow in this specification.

This invention, therefore, encompasses means for tra posing coded information from the control tape iti i to signals suitable for controlling, for example, the projection of successively formed character images upon a photosensitized material in a preestablished pattern, which pattern, in the particular embodiment of the invention sclected for purposes of illustration, comprises justified lines of characters forming columns leaving uniform marginal boundaries.

In accordance with the invention, the width of the column in which the characters are to be printed is represented by an electronic time base hereinafter termed column width pulse of commensurate length which is periodically swept out at a relatively high repetition rate. The actual position of the mirror i5 at any instant is given by a short electric position signal hereinafter cali-ed the position pulse having the same repetition rate as the time base or column width pulse and whose phase with respect to the time base is a function of the instantaneous position of the mirror with respect to its column beginning and column ending positions. For example, when the mirror 15 is in the column beginning and column ending positions, respectively, the position signals occur simultaneously with the beginning and end of the time base, and correspondingly for any mirror position between the column beginning and column ending positions.

The position that the mirror should have for proper positioning of a character to be printed is represented by another relatively short electric signal designated the guiding pulse herein. The guiding pulse is derived from code indicia on the control tape lr6 by an electronic circuit to be described later. Each relatively short guiding pulse, like each corresponding position pulse, occurs in time within the duration of a column width pulse of relatively long duration thereby to bear a particular time relationship thereto as indicative of position.

A suitable system for measurement or subdivision of the column width pulses to enable the respective positions of the guide and position pulses to be determined accurately as a function of time, is provided according to the invention and will be fully described later.

While the position pulses are indicative of the actual instantaneous positions of the mirror, the guiding pulses are indicative of the positions the mirror should have if the mirror 15 is to reflect the respective character images to their proper places on the hlm il. Both the position pulses and the guiding pulses are introduced as inputs into the galvanometer control circuit i9 which is adapted to actuate the galvanometer device i8 to rotate the mirror to the angular positions demanded by the guiding pulses, as described. The mirror 15 is thus effectively made to follow the guiding pulses in te composition of each line of characters.

The means for justifying the lines of characters printed on the lm 11 is incorporated in the guide pulse generating circuits. Briefly, the system measures, by an antecedent scanning system, the total length of each line of characters as a function of time. This measurement includes the spaces voccupied by the characters themselves, hereinafter called character spaces, as well as the spaces between successive Words or groupings of characters, hereinafter called word spaces.

The word spaces are utilized. in the illustrated embodiment of the invention to effect justification of the lines. A standard word space is provided which is inserted between words if no justification of the line is required, such as when a paragraph ends in the middle of aline. if justification is required, as when a fuil line is to be compose-fi, the system derives suitable word space values to bring the total line-length to its requisite dimensions.

Portions of the guide pulse generating circuits are duplicated i'n order that one of the duplicate circuits is available to perform the antecedent operation of measuring the next line to be composed and set itself up to insert the proper word spaces when its function is changed, by suitable switching means, to the composing or printing function. rl`he other duplicated circuit, on the other hand, after printing a given line reverts to the antecedent function of measuring the line subsequent to that then being printed by the other circuit.

There follows under appropriate sub-headings a description of suitable means for developing the respective pulses defined above, as well as a description of the circuits utilizing these pulses to control the angular positions of the mirror if?. The sub-headings, in order, are:

i. Column width pulse generating system.

ll. Position pulse generating system.

iii. System for measuring the positions of the guide and position pulses within the column width pulses.

iV. Guide pulse generating system (general overall description) IVG. Blaniring and cycle counting circuits. iVb. Word space delay generator circuits. iVc. Word space counting and distributing circuits.

. Function transferring and resetting circuits. Vl. Galvanometer control circuits. VH. Synchronizing circuits. Viti. Modication of word space delay generator. I. Column width pulse generator system (time base) (Fig. 4)

A pulse generating system is provided to supply the time base or column width information. This information may, according to the invention, be in the form of a succession of relatively long pulses, each having a time duration proportional to the width of the column. These column width pulses have a relatively high repetition rate, at least one pulse being provided for each character cr character space among the several which comprise a given line.

A typical system for generating these pulses comprises a rotatably mounted timing disc 23 having a plurality, for example twenty-five, of equally angularly spaced radial slots 25 adjacent its periphery. The disc is rotated by a motor 24 at a given rate, 12,000 R. P. M. (200 R. P. S.) being selected for purposes of illustration herein.

A source of light 29 such as a lamp (Fig. 4) is disposed to pass a beam of light through a lengthwise adjustable slot Stb in a plate 31, thereby to produce a strip or ribbon of iight having a width equal to the length of slot 39. The strip of light should impinge upon the timing disc 23 in a iine 30a which is disposed transversely of the intercepting radial slot 25. Passing through the radial slot, the light is received in the form of a long pulse by a photo-electric cell 32 through a suitable lens system 33. Each pulse is of relatively long time duration, which is equal to the time of traverse of one radial slot 25 across the width of the strip of light. This pulse is set up as a function of the column width and is, as stated, termed the column width pulse." An amplifier may be provided for intensifying these pulses.

Means are provided for altering the duration of this column width pulse by changing the width of the strip of light by any suitable means such as a screw-adjusted cover plate 34 overlying the slot 30 in the plate 3i.

Column width information is thus set up in terms of time by means of relatively long pulses of adjustabie duration having a frequency or repetition rate of 5,00() per second.

lt should be noted that the width of the strip of light impinging on the discs 25 in the line 30a should in all cases be equal to or less than the chord distance between adjacent radial slots 25 to prevent overlapping of successive column width pulses.

.The column width pulses from the photo-electric cell 32 are fed into the galvanometer control circuit 19 through a circuit including the amplifier 40, a conduit 41, a conduit 42, a second amplifier and differentiating circuit 43, and a conduit 44.

A useful time interval, hereinafter called the column sweep period may be derived from the column width pulses by measuring the time between the beginnings of two successive column width pulses. In the example set up for illustration, the column sweep period would be 200 microseconds, also having a frequency rate of 5,000.

II. Position pulse generating system Position pulses may be provided according to this invention by utilizing a second mirrored surface 15b (Fig. 4) on the mirror 15 to retiect a beam of light generated from a suitable source 20. The beam of light travels from the source 20, through an aperture 21a in a plate 21, through a lens system 22 to the surface 15b of the mirror 15, and thence to the surface of the timing disc 23 at a point p.

The slots 25 of the rotating disc 23 cross the beam of light reflected from the mirrored surface 15b, thereby causing intermittent flashes of light to be transmitted to a photo-electric cell 26. With each of the twenty-five radial slots intercepting the light beam at a rate of 200 per second, the photoelectric cell 26 receives 5,000 liashes of light per second, and therefore generates 5,000 electrical pulses per second, each being of relatively short duration 4as determined by the narrow width of the slots 25. These pulses as developed in the photocell 26 and intensied by an amplifier 27, are termed position pulses and are fed into the galvanometer control circuit 19 by a conduit 28.

III. System for measuring the positions of the guide and position pulses within the column width pulses (Fig. 4)

Means are provided according to the invention for determining the respective positions of, or timing of corresponding position and guide pulses within a corresponding column width pulse. This is accomplished by establishing a relatively high frequency signal, herein called the base frequency, whereby a relatively large number of cycles thereof are generated within the duration of each column width pulse.

The timing disc 23 may be utilized to provide this base frequency by providing a magnetic circumferential portion 23a upon which is magnetically recorded a succession of constant frequency sine-waves, an equal number, for example 200, being recorded between each pair of adjacent radial slots Z5. Thus 5000 waves would be recorded in the entire timing disc.

A magnetic pick-up 35, disposed at the periphery of the disc, is adapted to have induced therein sine-wave signals at a rate of one million per second (200 R. P. S. X 5000). These signals may be amplified by an amplier 36.

Assuming now that the column width pulse is adjusted to occupy, in time, three-fourths of the column sweep period (200 cycles of base frequency), there will be 150 cycles of base frequency in the duration of each column width pulse. Assigning a unit value of column width to each cycle, there is established a basis for measuring the column width time in terms of cycles of base frequency, and hence means for accurately measuring position across the column. The column width pulses, in the selected example, thus subtending 150 cycles of base frequency, the column width is divided into 150 parts.

. As the mirror 15 is rotated through its range of movement and the point p of impingement of the light beam upon the disc consequently changed, the position pulses are made to occupy successively all time locations in the column width pulses, as can be seen from Fig. 4. By measuring the number of cycles of base frequency that elapse between the beginning of the column width pulse and the occurrence of the position pulse, the angular position of the mirror 15 can be accurately determined.

IV. Guide pulse generating system The third and final series of signals or pulses introduced into the galvanometer control circuit 19 through a conductor 45 are the guiding pulses. The guiding pulses, as stated, are a function of the code signals from the control tape 10, and are generated at any given moment in either one of two duplicate guide pulse generating circuits 46 and 46 (Fig. 1b). These circuits are provided in duplicate in order that one can control the printing or composition of a line of characters on the film 11 by means of its output of guiding pulses while the other prepares for printing the next line, in which process it stores information to be utilized if the line requires justification.

As illustrated the guide pulse generating circuit 46 is supplying guiding pulses to the galvanometer circuit 19, while the guide pulse generating circuit 46 is preparing for the justification of the next line. these two circuits are interchanged in a manner, later described, after each line has been composed. Consequently, in the ow diagram (Figs. la, 1b and 1c) the guide pulse generating circuit 46 will be switched to perform the printing or composing function for the next line, while the companion circuit 46 will revert to preparation for the justification, if required, of the line following the next line.

The operation of the switching means provided for interchanging the functions of these two circuits will become apparent in the course of the detailed description under the sub-heading V entitled Resetting circuits.

The guiding pulse is timed to take a position within a column width pulse to indicate, as a funtion of time, the position that the character corresponding thereto is to assume on the film 11. Each guiding pulse is compared in the galvanometer control circuit 19, with a corresponding position pulse, and if a time discrepancy exists between the two pulses, the mirror is rotated to bring the position pulse into coincidence with the guiding pulse as described.

The control tape 10 (Fig. 1a) carries information pertinent to character selection, word spacing, character spacing, line ending, and justification (if required). For convenience in proof reading the tape carries characters 51 as they will appear in print in the film 11. Aligned with each character 51 are indicia (not identified) pertaining to the character selection. The circuits identified by phantom lines in Fig. l are responsive to these indicia, in a manner fully disclosed in the aforementioned ccpending application, to actuate the flashing lamp 13 and character disc 12 in timed relationship.

Also aligned with each character 51 are indicia 52 pertinent to character spacings. These indicia appear in clusters of short lines, the number of lines in each cluster being proportional to the physical space the character corresponding thereto will occupy in the print on the film 11.

Triangularly shaped indicia 53 are provided at each word ending and wherever else desired to designate a space such as that required between words.

Rectangularly shaped indicia 54 of relatively long length are provided to denote the termination of a line of characters.

Indicia 55 are placed on the tape adjacent lines of characters which require justification. These indicia appear whenever the characters plus spaces of any line exceed a certain proportion of the line space, thereby to indicate justification is required. The coded indicia may be in the form of darkened areas which intercept a light beam traveling from its source to photoelectric cells to generate a pulse therein.

As the coded tape 10 travels through the scanning area, it passes two sets of photoelectric cells 56-5'7 and 58-59-60 respectively.

The functions of The cells S6 and 57, comprising the antecedent scanning means, are activated by a suitable light source 61. The cell 57 is aligned to be controlled by the indicia 53 and 55 relating to word spacing and justification It will be noted that the indicia 53 and 55 have different contours and thus cause pulses to be developed in the cell 57 possessing characteristics which are distinguishable by the circuits into which they are led through a common conduit 72. This effect is fully described in the above noted copending application and will not be described in detail herein.

The cell 56 is controlled by the indicia 52 relating to character spaces.

The cells 58, 59 and 60, activated from a suitable light source 62, are concerned with the printing or composing function. The cell 58 is controlled by the indicia 52; the cell 59 by the indica 53 and 5S; and the cell 6G by the indicia 54 which indicate the end of each line.

The signals from the photoelectric cells 56, S7, S8, 59 and 60 are passed through the ampliers 63, 64, 65, 66 and 67, respectively, before being fed into the guide pulse generating circuits 46 and 46.

The amplified pulses from the photoelectric cell 69, called line pulses, are fed by means of a conduit 63 directly to a reset circuit 69 (Fig. lb) and to a changeover circuit 7G, each serving a particular' function to be described later.

The amplified pulses from the cell 56, termed antecedent character space signals, are fed by means of a conduit 71 to the movable relay contact arm 73 of a relay S1, which is adapted to engage either of two fixed contacts 73a and 73h. The pulses from the cell S7, termed antecedent Word space signals, and justifying signals, are led by the conduits 72:1 and 72, to the movable relay contact arms 77 and '75, respectively, of the relay Sl. The contact arm 77 is adapted to engage either of two tiXed contacts 77a and 77b while the contact arm 7S is adapted to engage either of two xed contacts 75a and 7511. The pulses conducted to the contact arm 75 are termed justifying signals, while those conducted to contact arm 77 are termed antecedent word space signals. The justifying pulses, if any, pass from the movable contact 75 to contact 75a, and through a conduit 36 to a relay S4, the function of which will be described later.

Amplified pulses from the cell Se termed printing character space signals and having their origin in thc code markings 52 are led by a conduit 73 to the movable contact arm 79 of the relay Si which is adapted to engage either of two fixed contacts 79a and '7%. Amp'iified pulses from the cell 59, termed printing word space signals, are led by means of a conduit Si) to the movable contact 81 of the relay Si, which is adapted to engage either of two tired contacts Sla and gli).

With the relay Si in the position shown in Fig. la the printing word space signals delivered at the relay movable contact arm 31 and the printing character space signals delivered at the relay movable contact arm '79 are fed to the guide pulse generating circuit d6 through the conduits 25' and S', respectively. Hence, the guide pulse generating circuit 46 is performing the printing function and is, therefore, supplying guiding pulses to thc galvanometer control circuit i9 through a circuit including conduit l', engaged relay contacts 91 and 92 of a relay S5, and the conductor 455. The relay S5 controls the movable contact l92 to engage selectively either the fixed contact 9 or a second fixed contact 19, depending upon which of the guide pulse generating circuits i or f5' is to perform the composing function.

Meana the antecedent character space signais and antecedent word space signals delivered at the reiay moral: Contact arms 73 and 77, respectively, are being fed to the guide pulse generating circuit i6 through the conduits 82 and S3, respectively. The circuit 46 utilizes these inputs to develop line justifying controls to be used in printing the line following that being printed by the circuit 46'.

In the following description, reference numerals will be assigned to the components of one (46) of the two duplicate guide pulse generating circuits, while like primed reference numerals will be applied to like components of the other (46').

The guide pulse generating circuit 46 includes a blanking circuit 37 connected by a conduit 91 to a cycle counting circuit SS. The blanking circuit 87 receives antecharacter space signals through the conductor 82 and base frequency pulses from the amplifier 36 through conduits 89 and 9i). The cycle counter 88 receives the output of the blanking circuit through the conduit 91.

The output of the cycle counter 3S is a pulse which is positioned in the column width pulse in accordance with the cumulative character space signals received from control tape iii. This pulse will be referred to as the "totalized character space pulse, hereinafter' termed thc t. c. s. pulse. The cycle counter 83 counts each cycle of the base frequency supplied from the amplifier 36 and generates one short-duration t. c. s. pulse for euch 200 cycles counted. The blanking circuit 87, however, causes one or more cycles of the base frequency to be obscured for each character space signal received from the control tape 10. The cycles obscured cause a gap in the counting, and hence delay the achievement of the total count of 200 necessary to establish a t. c. s. pulse by the number of cycles obscured.

If the t. c. s. pulses are timed initially to coincide with the beginning of a column width pulse, and then several cycles of the base frequency are blanked by the antecedent character space signals, the t. c. s. pulse will then lag the beginning of the column width pulse by the number of cycles blanked. When 150 cycles have been blanked the t. c. s. pulse will coincide with the ending of the column width pulse. The t. c. s. pulse can thus be described as moving along the column width pulse with its position being at all times proportional to the accumulated character space signals, and the accumulated space occupied by the characters in the line. The advancement of the t. c. s. pulse across the column width pulse is a matter of progressively delaying its occurrence with respect to the beginning of the column width pulse.

The guide pulse generating circuit 46 also includes a word-space generator 92, a word space counting and distributing circuit 93, and a discriminator circuit 9d. The word space generating circuit 92 receives t. c. s. pulses from the cycle counting circuit 8S through a conduit 95. The conduit S may be found in Figure lb. in Figures 2b and 2c this conduit is illustrated as including conductor 127. Antecedent word space sinnals are led from the engaged relay contacts 77 and 77a through the conduit 83 to the word space distributing and counting circuit 93. The discriminator 94 receives column width pulses through a circuit including the conduit 41 (from the timing disc 23) and a conduit 96, and the output of the discriminator is fed in turn to the word space distributing and counting circuit 93 through a conduit 97. A conduit feeds the output ot' the word space distributing and counting circuit 93 to the word space generator Q2. The conduit r as viewed in Figure lb includes conductor 37 in Figure 2c. The entire circuit 46 is thus provided with means for receiving all of the information required to justify the line of type it is next to compose.

instead of delaying the t. c. s. pulse an integral number of unit spaces to account for a word space, the t. c. s. pulse is delayed by a circuit whose delay may be adjusted to correspond to an irrational number of unit spaces. This allows exact justification of the composed line since Word spaces do not have to conform to unit width values.

The operation of the system, in short, is based upon the use of time as a dimension in measuring the width 9 of the column and in specifying the position in the composed line that each character is to take. The time duration of the column width pulses establishes the column width in terms of a time interval. The position within the composed line that a character is to take is given by the guiding pulse.

The guiding pulse is timed with respect to the column width pulse in accordance with the accumulated space occupied by preceding characters and word spaces. As a line of type is composed, the guiding pulse moves across or through the column width pulse indicating the position each character is to take. The angular position of the mirror accordingly is made to follow the progress of the guiding pulse through the use of the position pulse and galvanometer control circuit 19, the latter acting 1 as a servo system.

Fig. 5 shows the time relationships in the operation of the justifying and character positioning system. ln this figure, line l shows the base frequency as generated from the timing disc and line ll the column width pulse also as generated from the timing disc. Line lli shows the t. c. s. pulse as generated by the combination of the cycle blanking circuit 87 and cycle counter 8b.

As stated, for the positions of the relay contacts 79 and 8l shown, the printing character space signals and the printing word space signals are delivered to the guide pulse generating circuit 46. Printing character space information from the engaged relay contacts 79 and 79a is delivered through the conduit 84 to the blanking pulse generating circuit 37, and printing word space signals are delivered from the engaged relay contacts 81 and 0in to the word space distributing and counting circuit 93 through the conduit As in the guide pulse generating circuit d6, the cycle counter 88 receives base frequency pulses from the timing disc 23 through the conduits 09 and 90. Column width pulses are likewise delivered to the discriminator 94 through the conduits 4l and 96. The guide pulse generating circuit 46 is thus provided with means for receiving all of the information necessary for positioning characters in the line being composed by projection thereof on to the film ll by means of the mirror 15. (The circuit 46' has previously received antecedent and justifying signals relating to this line in the same manner that the circuit 46 is presently receiving antecedent signals for the following line.)

The cycle counter 0S', which is described later in detail under the sub-heading Blanlcing and cycle counting circuits, is of the step type which delivers a single short (time) duration pulse for every 200 cycles received. Therefore, the t. c. s. pulses delivered by the cycle counting or frequency divider circuit 88' have a frequency or repetition rate exactly equal to that of the column sweep or 5000 per second. By means of a counting synchronizer circuit 99 (Figs. 1b and 2c), these pulses initially are made to coincide with the beginning of the column width pulse as shown in lines II and HI of Fig. 5. This coincidence occurs at the beginning of the composition of each line.

As each printing character space signal is received from the control tape 10 by the blanking circuit 87 through a circuit including the photo-electric cell 58, the amplifier 65, the conductor 7S, the engaged contacts 79 and 79a of the relay Sl and the conductor S4', a number of cycles of the base frequency are blanked out and hence are not counted by the cycle counter S8. For example, assuming that each printing character space signal blanks one cycle of the base frequency going to the cycle counter S8', then if 20 printing character space signals have been received, the t. c. s. pulses from the cycle counter would be lagging their initial timing by the time occupied by 20 base frequency cycles, as shown in line Ill of Fig. 5, and would occupy a position in the column width pulse corresponding to 20 units of width.

The t. c. s. pulses from the cycle counter 88 are delivered through a conduit 95 tothe word space generator 92. As indicated, the latter has previously been set up by the antecedent signals to delay each t. c. s. pulse it receives by an amount of time which is equivalent to the accumulated word space to be inserted. The t. c. s. pulses, therefore, are delayed by an amount of time representing the required word space as shown in lines lV and V of Fig. 5.

The pulse shown in line V of Fig. 5 is the guiding pulse. This pulse is now positioned within the column width pulse corresponding to the position the next character to be printed is to take.

If the position pulse as shown by the full lines in line Vl of Fig. 5 occurs before the guiding pulse in time, the position of the mirror 15 will be lagging the required position along the column width. Such a time discrepancy between the two pulses will cause energy to be delivered to the galvanometer to rotate the mirror and move the character position ahead as previously described.

To establish the correct word space to justify the line next to be composed, the antecedent character space signals from the control tape l0 are delivered to the blanking circuit 87 of the guide generating circuit 46, and the blanking of cycles of the base frequency occurs as in the blanking circuit S7. Antecedent word space signals from the control tape are delivered to a word space distributing and counting circuit 93. From this circuits operation on the column width and t. c. s. pulses, a control voltage for the word space delay generator 92l is established. This control voltage adjusts its delay to a value which is equivalent to the total word space in the line to be composed. A detailed explanation of the operation of these circuits will appear later.

When the circuit 46 is transferred to the printing function (performed by the circuit 46 in the diagrams) by the operation of the relays S1 and S5, the total word space delay is divided into the individual word spaces by the word space counting and distributing circuit 93, and the guiding pulses are consequently delayed according to the accumulated word space to be inserted.

IVa. Blankz'ng and cycle counting circuits (Figs. 2b or 3a and 6) Referring now to Fig. 2b, antecedent character space signals from the control tape 10 are led to a conventional cathode-coupled one-shot multivibrator circuit comprising the vacuum triodes Vil and V2, the resistors R1, R2, R3, R4, R5 and R6, and the condensers C1, C2 and C3 connected as shown in the gure.

The antecedent character space signals are applied by means of a conductor 82 to the grid 100 of the tube V1 through the condenser C1. The pulses generated by this multivibrator circuit are of a predetermined length, and appear at the plate of the tube V2 to be coupled by means of a conductor 10S and the condenser C3 to the grid 106 of a gas triode V3. i

The gas triode V3 has a plate 107 connected to a suit able source of positive potential through a resistor R7 and is normally nonconducting. To ionize or render the tube V3 conducting requires the simultaneous application to the grid 106 of positive voltages from the multivibrator circuit through the conductor as well as positive voltages through conductor HI8 and a resistor R8 from the cathode 109 of a vacuum triode V4 which is connected as a cathode follower. The grid 112 of the tube V4 is connected by a conductor 113 to the plate 111 of a tetrode V5, one grid 110 of which receives the base frequency from the timing disc 23 through the conductor 90. The tube V5 functions as a clipping amplifier to produce square waves of the base frequency at its plate 111 which is connected to a source of positive potential through a resistor R10.

The grid bias on the gas tube'V3 is so arranged that positive pulses from the multivibrator and from the tube V must appear simultaneously to initiate conduction in the tube V3, as stated. A network 115 is connected to the plate 107 of the tube V3 by a conductor 116, and also to a source of positive plate potential through the resistor R7. The network 115 may comprise, for example, a series inductance 117 and a plurality of shunt condensers 11S, the latter being adapted to be charged through the resistor R7. When the tube V3 is rendered conducting, the network 115 discharges through a resistor R11, causing a pulse of voltage of comparatively constant amplitude to be developed across the latter. This voltage is fed by a conductor 12 to second grid 121 of the tube V5, which pulse biases this tube beyond cut-oit, thereby preventing its operation during the interval when the network 115 is discharging.

The time relationships involved in the operation ot the previously described blanking and pulse generating circuits 87 are shown schematically in Fig. 6. Line i in that figure shows the base frequency from the disc 23 (Fig. 4) which is applied to the grid 110 of the tube V 5. Line II shows a character space signal as it is received from the conductor 32 and fed to the blanking circuit S7. The timing of the character space signal with respect to the base frequency may be random. Line IH shows the multivibrator output pulse which is applied to the grid 196 of the gas triode V3. This output pulse may also be randomly timed with respect to the base frequency. Line 1V shows the square wave output appearing across the resistor R9 and which is also applied to the grid 136 of the gas triode V3. Line V shows the total voltage applied to the grid 106, which is the sum of the two voltages shown in lines HI and 1V.

As indicated in line V1, the total voltage when a pulse is generated by the multivibrator exceeds the critical voltage of the tube V3 so that the latter becomes conducting and discharges the network V5. This results in the application of a blanking pulse (line V1 of 6) to the grid 121 of the tube V5, momentarily biasing the latter beyond cut-off. As a result, one pulse in the output at the plate 111 of the tube V5 is blanked out, as shown in line VII of Fig. 6, and is, therefore, not counted by the counter receiving the output of the tube V5.

It should be noted that the blanking voltage begins simultaneously' with the rise in the rst square wave of line 1V which follows initiation of the multivibrator output pulse (line Hl) and is between one and one and one-half cycles in time duration. This is to insure the blanking of one complete cycle. When the network 115 is completely discharged, it will not produce another blanking pulse until it has had time to recharge through the resistor R7. The blanking voltage is not reapplied, therefore, the second time the total voltage at the grid ot the as triode V3 exceeds the critical voltage as shown at the point a in line V.

Different point sizes of type for the characters may be accommodated by changing the time duration of the pulse developed by the discharging network 115 so as to blank integral numbers of cycles in proportion to the type sizes desired. Networks with different pulse duration times may be switched in or out of the circuit by suitable relays, for example, to effect this result.

In the form of the invention shown in Fig. 2b, a two stage, step type counter is used. The rst counter stage comprises the vacuum diodes V6 and V7, and the condensers C4 and C5, the voltage developed across the condenser C5 being fed to a conventional blocking oscillator circuit 122 including the vacuum triode V8. rThe input to the rst counter stage is the square wave output from the tube V5, the plate 111 of the latter being connected to the condenser C4 by a conductor 123. The pulses appearing at the plate 124 of the tube V8 are fed to a second counter stage comprising the vacuum diodes V9 and V13 and the condensers C6 and C7. The voltage developed across the condenser C7 is fed to a conventional blocking oscillator circuit 125 including a vacuum triode VII which delivers a pulse at its plate 126. The operation and construction of step counters of this type are well known and a detailed description thereof need not bc given herein. Sufce it to say that a single pulse called a t. c. s. (totalized character space) pulse, is dcveloped at the plate 126 of the tube VII for each 2G@ pulses fed to the rst stage of the counter from the tube V5.

Obviously, any other suitable cycle counter means, such as pulse counters of the binary type, may be used ir. lieu of the system just described. Such pulse counters are well known in the art and a complete description of scale of two counters may be found in vol. 19 of the Radiation Laboratory Series published by the McGrawi-lill Book Co., entitled waveforms by Chance, Hughes MacNichol, Sayre and Williams at chap. 17, pages 604 to 612. Binary counters are also disclosed and described in the Handbook of Industrial Electronic Circuits by Marcus and Zelef.

IVb. Word space delay generator circuits (Figs. 2c or 3b and 7) During the justifying cycle of the guide pulse generating circuit 46, the t.c.s. pulses from the plate 126 of the tube V11 in the cycle counter 85 are applied through a conductor 127 and a condenser C8 to a grid 128 of a pentagrid vacuum tube V12. The tube V12 is connected as a so-called phantastron time delay circuit, a description of which is given in Electronics magazine for April 1948, beginning at page 100. The circuit utilizes a pentagrid vacuum tube V13 as a dynamic load resistor to obtain a uniform rate of change in the mutual conductance of the tube down to zero plate voltage.

The operation of this phantastron circuit is such that a constant voltage output pulse is obtained, in response to and immediately following each t.c.s. input pulse, which output pulse is proportional in its duration to the magnitude of a control voltage, the source of which is the "Word space counting and distributing circuit to be described. The variable duration output pulse of the phantastron is then diiferentiated to obtain a guide pulse for controlling the position of the mirror 15', as described.

The tube V14 is a cathode follower having a load resistance R12 connected by a conductor 129 to a grid 136 of the tube V12, its grid 131 receiving the output of the latter tube through a condenser C10 in series with a conductor 132. The vacuum tube V15 is a plate voltage limiting diode, the anode 133 of which is connected to the plate 134 of the tube V12 by a conductor 135, and the cathode 136 of which is connected through a resistor R13, a conductor 137, a movable switch Contact 138 on a relay S2, engaging a xed contact 13?, and a conductor 140 to the cathode 1-11 of a tube V16. The tube V16 is a cathode follower, the cathode 141 of which is connected to ground through a resistor R14 and the grid 142 of which receives a control voltage developed across a condenser C11 through a conductor 143. The condenser C11 is connected to a fixed contact 148 on a relay S3 which is engaged by a movable contact 149 connected to the plate 161 of the tube V19. These connections enable the condenser C11 to be charged through the plate resistor R17.

The tube V17 is a cathode follower having its grid 1493 connected through a condenser C12 and a conductor 145 to the cathode of the tube V12, which is connected to ground through a resistor R15. The condenser C12 cooperates with a grid leak resistor R16 for the tube V17 to form a differentiating circuit to produce a positive guiding pulse at the end of the delay time of the circuit (i. e. at the end of the variable duration pulse at the cathode 155 of the tube V12).

lt will be recalled that, during the justifying cycle, the next line of copy to be printed is being scanned by the antecedent scanning mechanism comprising the photoelectric cells 56 and 57 (Fig. 1a). Prior to the receipt of the first character space signal, the t.c.s. pulses appear- 

